Using lego parts for building mosaics is an old idea but, surprisingly, the LEGO company released a mosaic set only in 2000 with the 3443 set. A rapid search on the web displays a huge panel of methods for using all possible LEGO parts for reproducing all kind of pictures. Recently, dedicated softwares (Bricksaic and PicToBrick) allow to get directly the inventory of the parts needed for a given image making mosaic building more easier. However, most of the buildings show only a single static picture and are finally similar to painting. In exhibitions, mosaic impress certainly but, compared to dynamic layouts, they do not pay attention too long to the visitors. Here, a new kind of mosaic, called bi-mosaic, is introduced allowing to display two pictures on the same building depending on the viewing angle. The technic is based on an alternance of direct (black for exemple) and inversed slopes (grey for exemple) as shown in the picture below. Depending on the viewing angle, you see the black or the grey face.

Now we know the technic, lets make it in real into the framework of the magical world of Harry Potter where paintings on the walls of the Hogwarts castle change all the time. The idea is to show Harry Potter face from one viewing angle and lord Voldemort from the other one (remember that a part of Voldemort spirit belongs to Harry).
So I took two pictures of LEGO minifig faces slightly distorted in order to take into account that a pixel corresponds to 13.5 mm times 8 mm when viewed with an angle of 45 degrees (see picture below).

I used the BrickSaic software to get a MLCAD file for each picture. In order to put the two pictures into a single Bi-mosaic, using MLCAD, I build first a special file having 60 columns made of 102 direct 1x2 slopes and 102 inverse 1x2 slopes. With excel, after having sorted the slopes, I did a copy-paste of the colour code of the Harry Potter BrickSaic file on the colour code of the inverse slopes and the same for Voldemort for the direct slopes. Now, I have an MLCAD file of the Bi-mosaic made of 1x2 slopes and I can check that everything is in order from the point of view of the colour codes.
However, such a building is not stable because the rows are not connected. Consequently, we have to use 1x2 and 2x2 inverse slopes and 1x2, 2x2, 3x2, 4x2 and 8x2 direct slopes instead of only 1x2 slopes. I did this by hand during a few hours to get the final MLCAD file.
With LDView, I could also check the transition from one face to the other which can be seen on the following video.

I started to work on this building on February 2011 aiming to present it end of June at Fana�briques 2011. I finished the MLCAD file end of March, ordered the missing parts during April and built the mosaic during several evenings in May.

You can see the final result at the exhibition on the following picture and videos.

hi there! awesome idea! i am planning on making a superman/batman logo lenticular mosaic similar to yours. would i be able to just use the 2x2 and 1x2 regular and inverse slopes as a 1 to 1 match to the bricksaic 'block' pixel that is made for you with the software? or would i have to do all the math and calculations you did for your HP/V mosaic?
if you need to, you can email me at chawan_cut@yahoo.com
thanks!

Quoting daevster !
Clever techniques! I've never seen anything done like this before :)

Thanks. I was also surprised that nobody used it before (to my knowledge) because it is finally simple and using MLCAD is a good help because each column can be separated from the others. As mentionned, Arthur Gugick has build a mosaic with a similar effect inspired by the Portrait of Dorian Gray by Chris Doyle (http://www.flickr.com/photos/reasonablyclever/sets/72157623404093536/) using cheesecake parts.
But I discovered their works only after Arthur commented on the first presentation of this mosaic.